python calls structures and functions of C programs

The C code is as follows:

#include

typedef struct TestDLL_

{

int a;

char *b;

} testdll;

testdll test( testdll t)

{

t.a=t.a+t.a;

printf("%dn%sn",t.a,t.b);

return t;

}

python The code is as follows:

from ctypes import *

#Absolute path

dllpath='test.dll'

dll=CDLL(dllpath)

#Python internal parameter assignment

a=c_int(125)

b =c_char_p('Hello world,Hello Chengdu')

#Define structure

class testdll(Structure):

_fields_=[('a',c_int),

                                     )]

#Instantiate and assign

t=testdll()

t.a=a

t.b=b

#Set the return value type

dll.test.restype=testdll

#test

t=dll.test(t)

print t.a

print t.b

x=raw_input('any key to continue')